I've been doing group rides with the same club for 23 years. The longer rides (70-100 miles) usually stop around 25 or 30 miles. Depending on who is there it may be a quick or long stop.
I think long stops are fine, starting up again is no big deal and I like to eat.

If you want to try a group ride, just show up and tell them you are a newbie and they will advise you. With us if you get dropped you may have to find your own way back. It's also not a big deal.
You will eventually make friends and find out who you like riding with.